In recent years, the commercial market for memory has gradually shifted from that for personal, desk top computers to consumer devices such as handheld or portable music players, communication devices, computing devices, and combinations of these features in one device. Due to the smaller and smaller size of these portable devices, memory with higher density and speed, lower power consumption, and small size is in high demand.
Extensive development has been directed to non-volatile memory devices including FLASH, polymer random access memory (RAM), magnetic RAM (MRAM), ferroelectric RAM (FeRAM) and resistance RAM (RRAM). Magnetic shift registers have been proposed as an alternative to these RAM devices, as magnetic shift registers can store and access a large number of data bits using just a few logic elements and a low cost.
In the magnetic shift registers, data writing and reading is accomplished by moving magnetic domain walls to a certain location within a magnetic track by current. To facilitate the storage of data, various embodiments of shift registers include an element in the track to support or stabilize a domain wall at a certain location during idle mode.
There is always room to provide better means to support or stabilize the domain walls.